Okazaki Yuka O, De Weerd Peter, Haegens Saskia, Jensen Ole
Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, 6500 HB Nijmegen, The Netherlands.
Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, 6500 HB Nijmegen, The Netherlands; Department of Cognitive Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands.
Brain Res. 2014 Nov 24;1590:56-64. doi: 10.1016/j.brainres.2014.09.058. Epub 2014 Oct 5.
Previous M/EEG studies on visuospatial attention have shown that attending to one hemifield, while ignoring the other, leads to a decrease in occipito-parietal alpha power contralateral to the target and a concurrent ipsilateral alpha increase. Here, we tested whether this alpha modulation facilitates the processing of attended faces in the presence of distracters. Face processing was tested in a match-to-sample task, in which participants matched a target face in a cued hemifield to a previously seen sample face. The target faces in the cued hemifield were presented together with a distracter face (intact or scrambled faces) in the other hemifield. The behavioral data indicated a larger impairment of matching performance when the distracter was another face, rather than a scrambled face. We hypothesized that enhanced alpha power contralateral to the distracter would enhance target matching by decreasing the interference from similar distracters. We found this effect, but only in the left hemisphere. Moreover, we found that with targets contralateral from the left hemisphere, a down-regulation of relative alpha power in the left hemisphere also correlated with increased target matching performance. Hence, the left hemisphere could protect the target from distracter interference either by decreasing alpha power in response to a contralateral target, or increasing alpha power to a contralateral distracter. Remarkably, alpha power in the right hemisphere was not predictive for matching performance. These findings support the hypothesis that alpha modulations contribute to the suppression of task-irrelevant information, but suggest a dominant role herein of the left hemisphere during face matching in the presence of distracters.
以往关于视觉空间注意力的脑磁图/脑电图（M/EEG）研究表明，专注于一个半视野而忽略另一个半视野，会导致与目标对侧的枕顶叶α波功率下降，同时同侧α波增加。在此，我们测试了这种α波调制在存在干扰物的情况下是否有助于对被关注面孔的处理。在一个样本匹配任务中测试面孔处理能力，在该任务中，参与者将提示半视野中的目标面孔与之前看到的样本面孔进行匹配。提示半视野中的目标面孔与另一个半视野中的干扰面孔（完整或打乱的面孔）同时呈现。行为数据表明，当干扰物是另一张面孔而非打乱的面孔时，匹配表现的受损更大。我们假设，干扰物对侧增强的α波功率会通过减少来自相似干扰物的干扰来增强目标匹配。我们发现了这种效应，但仅在左半球。此外，我们发现，对于来自左半球对侧的目标，左半球相对α波功率的下调也与目标匹配表现的提高相关。因此，左半球可以通过响应于对侧目标而降低α波功率，或对对侧干扰物增加α波功率，来保护目标免受干扰物的干扰。值得注意的是，右半球的α波功率对匹配表现没有预测作用。这些发现支持了α波调制有助于抑制任务无关信息的假设，但表明在存在干扰物的情况下进行面孔匹配时，左半球在此过程中起主导作用。
